As a developer used for electrophotography there is known a two-component developer comprising a toner and a carrier.
As the carrier there is conventionally known a resin-coated carrier prepared by coating a fluororesin on the surface of magnetic particles in order to prevent a toner substance from sticking onto the surface as described in Japanese Patent O.P.I. Publication (hereinafter referred to as JP O.P.I.) Nos. 209754/1983, 16617/1985 and 240758/1984.
As the toner there is known a toner which, in order to improve the fixability and fluidity thereof, comprises colored particles and hydrophobic silica particles, in which the colored particles contain a resin obtained by the reaction between the carboxy group present in a copolymer component and a multivalent metal compound, as described in JP O.P.I. No. 217358/1988.
However, a developer comprising the fluororesin-coated carrier is so poor in the powder fluidity that the developer, when supplied to a developing area, is liable to form a layer having an uneven thickness to result in the formation of an image having poor fine line reproducibility and solid image density uniformity; is fogged soon to have a poor durability; and has a problem that, when used in continued generation-to-generation copying from a copied image, the fine-line details are liable to blur even in an earlier generation copy image.